Express this product in scientific notation: $(4.00\times 10^{4})\times (7.00\times 10^{-4})$
Start by collecting like terms together. $= (4.00\times 7.00) \times (10^{4}\times 10^{-4})$ When multiplying exponents with the same base, add the powers together. $= 28.0 \times 10^{4\,+\,-4}$ $= 28.0 \times 10^{0}$ To write the answer correctly in scientific notation, the first number needs to be between $1$ and $10$ . In this case, we need to move the decimal one position to the left without changing the value of our answer. $ $ We can use the fact that $28.0$ is the same as $2.800 \times 10$ $ = {2.800 \times 10} \times 10^{0} $ $= 2.800\times 10^{1}$